1. Field of the Invention
The present invention relates to a technique for performing printing by depositing dots on a printing medium, and more particularly to a technique for the efficient supply of ink from the main tank to the sub-tanks that are arranged at different heights in the printing apparatus.
2. Description of the Related Art
In recent years, the ink jet printer has come into widespread use as an image-printing device. Among such printers, there are those that include a main tank and a plurality of sub-tanks as the ink holding tank. The sub-tanks are provided on the carriage, and the main tank is provided outside of the carriage. Ink held in the sub-tank is used for printing, and then ink is replenished from the main tank during the period between printings. The supply is made at once for each of the sub-tanks having low levels of remaining ink. Such a technique is disclosed, for example, in JP2001-232806A.
In this type of printer, in which sub-tanks are provided at different heights, it is preferable that ink is supplied at a certain pressure that allows ink to be supplied to the sub-tank at the highest position. However, because ink is supplied with such pressure from the main tank, the ink supplied to the sub-tank in the lowest position sometimes seeps out from the nozzle because of the high pressure. Accordingly, when ink is supplied to the sub-tanks, the carriage is moved to the refuge area and is capped by its nozzle surface.
The present invention was designed to address this problem. Accordingly, one object of the present invention is to provide ink efficiently from the main tank to the sub-tanks which are located at different heights in the printing device.